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ANNUAL REPORT FOR 2003
Tucker Mitigation Site
Currituck County
Project No. 6.049009T
TIP No. R-2228WM
Prepared By:
Office of Natural Environment & Roadside Environmental Unit
North Carolina Department of Transportation
December 2003
TABLE OF CONTENTS
SUMMARY............................................................................................................1
1.0 Introduction.................................................................................................2
1.1 Project Description...........................................................................2
1.2 Purpose ...........................................................................................2
1.3 Project History .................................................................................4
1.4 Debit Ledger ....................................................................................4
2.0 Hydrology ...................................................................................................5
2.1 Success Criteria...............................................................................5
2.2 Hydrologic Description ....................................................................5
2.3 Results of Hydrologic Monitoring .....................................................7
2.3.1 Site Data ...............................................................................7
2.3.2 Climatic Data.........................................................................8
2.4 Conclusions ...................................................................................11
3.0 Vegetation ................................................................................................11
3.1 Success Criteria.............................................................................11
3.2 Description of Species ...................................................................11
3.3 Results of Vegetation Monitoring ...................................................13
3.4 Conclusions ...................................................................................14
4.0 Overall Conclusions and Recommendations............................................14
TABLES
Table 1 – Tucker Tract Debit Ledger.....................................................................4
Table 2 – 2003 Hydrologic Monitoring Results......................................................7
Table 3 – Hydrologic Monitoring Results (1999-2002) ..........................................8
Table 4 – Vegetation Monitoring Results.............................................................13
FIGURES
Figure 1 – Site Location Map ................................................................................3
Figure 2 – Monitoring Gauge Location Map ..........................................................6
Figure 3 – 2003 Hydrologic Monitoring Results.....................................................9
Figure 4 – 30 – 70 Percentile Graph ...................................................................10
APPENDICES
Appendix A – Gauge Data Graphs
Appendix B – Site Photos/Photo and Plot Locations
1
SUMMARY
The following report summarizes the monitoring activities that have occurred in the past
year at the Tucker Tract Mitigation Site. This is the fifth year that the site has been
monitored for hydrologic and vegetation success. The site must demonstrate both
hydrologic and vegetation success for a minimum of five years to demonstrate
successful mitigation.
The Tucker Tract contains eleven groundwater-monitoring gauges. An Infinity tipping
bucket rain gauge was installed in August 2000. The daily rainfall data depicted on the
monitoring gauge graphs is recorded from this onsite rain gauge. An offsite rain gauge
recorded at Elizabeth City and maintained by the NC State Climate Office, contributed
to the daily rainfall data and historical rainfall data used for the 30-70 percentile. Twelve
vegetation-monitoring plots are used to monitor the twenty-five acres planted in trees on
the site.
The 2003-year represents the fifth growing season that hydrologic data has been
analyzed. All of the groundwater monitoring gauges met the success criteria with
saturation in the upper twelve inches for at least 12.5% of the growing season. Also, the
data from the groundwater gauges exhibit similar saturation periods as the reference
gauges.
At the request of the resource agencies, NCDOT performed supplemental planting of
baldcypress trees in and around plots 8, 9, 10, and 11 (Zone 1) in March 2003. The fifth
year vegetation monitoring of the planted areas revealed an average density of 397
trees per acre, which is above the minimum requirement of 260 trees per acre.
Based on the hydrologic and vegetation monitoring, the Tucker Tract Mitigation Site met
the success criteria for the site during the 2003-growing season. The site has
demonstrated both hydrologic and vegetation success for five consecutive years.
NCDOT proposes to discontinue hydrologic and vegetation monitoring on the Tucker
Tract Mitigation Site.
2
1.0 INTRODUCTION
1.1 Project Description
The Tucker Tract Mitigation Site is located in Currituck County (Figure 1). This site is
part of a large property consisting of 68.3 acres. Approximately 48.1 acres have been
set aside for mitigation. Approximately 28.2 acres of the 48.1 acres were developed
and constructed as the Tucker Tract Mitigation Site. The remaining 20.2 acres will be
reserved for possible future mitigation projects. The site was built to mitigate for the
widening of NC 168 (TIP Project R-2228). The project includes the restoration of 25.1
acres of PC agricultural fields to forested wetlands and the preservation of 2.8 acres of
forested wetlands and 8.7 acres of timbered wetlands.
The Final Mitigation Plan for this site was issued on April 1, 1996. Initial construction
was completed in late 1997. At that time, it was determined that the site had been
graded to an unacceptable level. A second contract was issued and the site was re-graded
in 1998 with completion in September 1998. The site was planted in early 1999.
In March 1999, NCDOT installed hydrologic monitoring gauges. In 2000, two additional
gauges were installed as a result of the field review by the resource agencies. The two
additional gauges were placed to track groundwater in the vicinity of Gauge TT-6.
Gauge TT-6 is located at an elevation that ranges from 0.7 to 1.0 foot higher than the
adjacent topography. This elevated area was delineated with GPS equipment and found
to be 0.09 acres in area. Based on the comments at an agency field review in May
2002, Gauge TT-6 was removed from the site. Twelve plots were established to
monitor vegetation on the Tucker Tract.
1.2 Purpose
In order to demonstrate successful mitigation, hydrologic and vegetative monitoring
must be conducted for a minimum of five consecutive years or until the site is deemed
successful. Success criteria are based on federal guidelines for wetland mitigation.
These guidelines stipulate criteria for both hydrologic conditions and vegetation survival.
The following report details the results of hydrologic and vegetative monitoring during
the 2003-year at the Tucker Tract Mitigation Site, as well as local climate conditions
throughout the growing season.
3
4
1.3 Project History
December 1997 Site Construction Completed (Contract 1)
September 1998 Site Construction Completed (Contract 2)
March 1999 Site Planted, Monitoring Gauges Installed
October 1999 Vegetation Monitoring (1 yr.)
March – November 1999 Hydrologic Monitoring (1 yr.)
August 2000 Vegetation Monitoring (2 yr.)
March – November 2000 Hydrologic Monitoring (2 yr.)
July 2001 Vegetation Monitoring (3 yr.)
March – November 2001 Hydrologic Monitoring (3 yr.)
July 2002 Vegetation Monitoring (4 yr.)
March – November 2002 Hydrologic Monitoring (4 yr.)
October 2003 Vegetation Monitoring (5 yr.)
March – November 2003 Hydrologic Monitoring (5 yr.)
1.4 Debit Ledger
Table 1: Tucker Tract Debit Ledger
Tucker Farm Mit. Plan Ratios TIP DEBIT
Habitat Acres
At Start:
Acres
Remaining
%
Remaining R-2228A, BA
SPH Restoration 25.1 0 0.0 25.1
SPH Preservation 2.8 0 0.0 2.8
Upland Mgmt. 8.7 0 0.0 8.7
TOTAL 36.6 0 0.0 36.6
5
2.0 HYDROLOGY
2.1 Success Criteria
In accordance with Corps guidelines for wetland mitigation, the success criteria for
hydrology state that the area must be inundated or saturated (within 12” of the surface)
by surface or groundwater for at least a consecutive 12.5% of the growing season.
Areas inundated for less than 5% of the growing season are always classified as non-wetlands.
Areas inundated between 5% - 12.5% of the growing season can be
classified as wetlands depending upon factors such as the presence of wetland
vegetation and hydric soils.
The growing season in Currituck County begins March 20th and ends November 13th.
These dates correspond to a 50% probability that temperatures will drop to 28°F or
lower after March 20 and before November 13.1 The growing season is 239 days;
therefore, optimum hydrology requires inundation or saturation for 12.5% of this season,
or at least 30 consecutive days. Local climate must also represent average conditions
for the area.
Based on the mitigation plan, hydrologic success is based on soil saturation that is
similar to the reference ecosystem and in accordance to Corps guidelines. The
reference ecosystem is located onsite in an undisturbed wetland located at a slightly
lower elevation in the southern portion of the site; gauges TT-8 and TT-9 monitor the
reference area.
2.2 Hydrologic Description
There are eleven monitoring gauges and one rain gauge installed onsite (Figure 2).
The automatic monitoring gauges record daily readings of groundwater depth. This is
the fifth year of hydrologic monitoring on the site.
The principal hydrologic source for this site is precipitation with some input from
Buckskin Creek. The Tucker Tract Site involved the grading of the field crowns and
placing the excess into several drainage ditches to prohibit water from leaving the site.
An additional seven to nine inches of fill was brought in to bring the site elevation to its
final grade. Several earthen berms were constructed adjacent to the lower areas of the
site and adjacent to the residential area. This design will restore wetland hydrology,
restrict infiltration losses and surface runoff, and avoid flooding the adjacent residential
area. The hydrologic monitoring should show the reaction of the groundwater level to
specific rainfall events.
1 Natural Resources Conservation Service, Soil Survey of Currituck County, North Carolina, p.71.
6
7
2.3 Results of Hydrologic Monitoring
2.3.1 Site Data
The maximum number of consecutive days that the groundwater was within twelve
inches of the surface was determined for each gauge. This number was converted into
a percentage of the 239-day growing season. The results are presented in Table 2.
Appendix A contains a plot of the groundwater depth for each monitoring gauge and the
surface water depth recorded by the surface gauge. The maximum number of
consecutive days is noted on each graph. The individual precipitation events, shown on
the monitoring gauge graphs as bars, represent data collected from the onsite rain
gauge.
Table 2. 2003 Hydrologic Monitoring Results – Groundwater Gauges
Monitoring
Gauge <5% 5-8% 8-12.5% >12.5% Actual % Dates of Success
TT-1+ r 61.1 March 20-August 12
TT-2 r 46.0 March 20-July 7
TT-3+ r 100 March 20-Nov 13
TT-4+ r 100 March 20-Nov 13
TT-5 r 45.6 March 20-July 6
TT-7+ r 100 March 20-Nov 13
TT-8 (REF)+ r 69.5 March 20-Sept 1
TT-9 (REF)+ r 100 March 20-Nov 13
TT-10 r 23.0 March 20-May 13
TT-11 r 43.5 March 20-July 1
TT-12+ r 100 March 20-Nov 13
+ Gauge met the success criterion during an average rainfall month (July, August, and
October).
*The two reference gauges are shaded.
8
Table 3. Hydrologic Monitoring Results (1999-2002)
Monitoring
Gauge
1999 %
Results
2000 %
Results
2001 %
Results
2002 %
Results
TT-1 16.3 No Data 23.4 26.8
TT-2 17.2 38 10 29.3
TT-3 9.2 25 73.5 53.1
TT-4 21.8 100 61.7 32.2
TT-5 8.8 33 39.1 32.2
TT-6 3 8 4.6 Pulled
TT-7 36.8 100 71.9 35.6
TT-8 (REF) 36 94 61 31.4
TT-9 (REF) 28.9 100 74.4 13.8
TT-10 18.4 33 26.7 26
TT-11 35 28
TT-12 43.8 33
Climate
Conditions
Average
Rainfall
Average
Rainfall
Below
Average
Rainfall
Average to
Below
Average
Rainfall
*The two reference gauges are shaded.
Table 3 is a summary of the hydrologic gauge data representing previous years (1999-
2002).
Figure 3 provides a graphical representation of the hydrologic results. Gauges
highlighted in blue indicate wetland hydrology for more than 12.5% of the growing
season. Gauges highlighted in red show hydrology between 8% and 12.5% of the
growing season, while those in green indicate hydrology between 5% and 8%. Gauges
highlighted in gray indicate no wetland hydrology (less than 5% of the growing season).
2.3.2 Climatic Data
Figure 4 is a comparison of monthly rainfall for the period of November 2002 through
November 2003 to historical precipitation (collected between 1972 and 2003) for
Elizabeth City, North Carolina. This comparison gives an indication of how 2003 relates
to historical data in terms of climate conditions. The NC State Climate Office provided
all local rainfall information.
For the 2003-year, January (02’) and November experienced below average rainfall.
The months of December (02’), July, August, and October recorded average rainfall for
the site. November 02, February, March, April, May, June, and September experienced
above average rainfall. Overall, 2003 experienced an average to above average rainfall
year.
9
Figure 3. 2003 Hydrologic Monitoring Results
10
FIGURE 4. 30-70 Percentile Graph
Tucker 30-70 Percentile Graph
Elizabeth City, NC
0
1
2
3
4
5
6
7
8
9
10
Nov 02' Dec 02' Jan 03' Feb 03' Mar 03' Apr 03' May 03' Jun 03' Jul 03' Aug 03' Sep 03' Oct 03' Nov 03' Dec 03'
Month
Precipitation (in.)
2002 Rainfall 2003 Rainfall 30th Percentile 70th Percentile
30th Percentile
70th Percentile
11
2.4 Conclusions
The 2003-year represents the fifth growing season that hydrologic data has been
analyzed. All of the groundwater monitoring gauges met the success criteria with
saturation in the upper twelve inches for at least 12.5% of the growing season. Also, the
data from the groundwater gauges exhibit similar saturation periods as the reference
gauges.
This is the fifth consecutive year that the site hydrology has met the success criteria;
therefore, NCDOT proposes to discontinue hydrologic monitoring.
3.0 VEGETATION: TUCKER TRACT MITIGATION SITE
(YEAR 5 MONITORING)
3.1 Success Criteria
NCDOT will monitor the site for five years or until success criteria are met. A 320 stems
per acre survival criterion for planted seedlings will be used to determine success for
the first three years. The required survival criterion will decrease by 10% per year after
the third year of vegetation monitoring (i.e., for an expected 290 stems per acre for year
4, and 260 stems per acre for year 5). The number of plants of one species will not
exceed 20% of the total number of plants of all species planted.
3.2 Description of Species
The following tree species were planted in the Wetland Restoration Area:
Zone 1: Wetland Reforestation (14.05 Acres)
Fraxinus pennsylvanica, Green Ash
Quercus falcata var. pagodaefolia, Cherrybark Oak
Quercus michauxii, Swamp Chestnut Oak
Quercus phellos, Willow Oak
Quercus nigra, Water Oak
Quercus lyrata, Overcup Oak
Nyssa aquatica, Water Tupelo
12
Zone 2: Wetland Reforestation (9.04 Acres)
Taxodium distichum, Baldcypress
Fraxinus pennsylvanica, Green Ash
Quercus falcata var. pagodaefolia, Cherrybark Oak
Quercus michauxii, Swamp Chestnut Oak
Quercus phellos, Willow Oak
Quercus lyrata, Overcup Oak
Zone 3: Wetland Reforestation (1.89 Acres)
Quercus phellos, Willow Oak
Quercus nigra, Water Oak
Fraxinus pennsylvanica, Green Ash
Taxodium distichum, Baldcypress
Quercus lyrata, Overcup Oak
Nyssa aquatica, Water Tupelo
Quercus michauxii, Swamp Chestnut Oak
13
3.3 Results of Vegetation Monitoring
Table 4. Vegetation Monitoring Results
Site Notes: Site is well vegetated with various grasses, a variety of Juncus sp., and
sedges. 6 to 8 inches of standing water noted in a small area of plot 7. Other species
noted: volunteer pines, Scirpus sp., Aster sp., cattails, Baccharis halimifolia, foxtail,
woolgrass, fennel, pickerel-weed, Cyperus sp., pennywort, Panicum sp., Lespedeza sp.,
red maple, sawgrass, and Sesbania sp.
At the request of the resource agencies, NCDOT performed supplemental planting of
baldcypress trees in and around plots 8, 9, 10, and 11 (Zone 1) in March 2003.
1 4 12 2 8 5 5 32 55 396
5 1 10 10 10 2 33 48 468
8 16 10 1 5 5 37 52 484
9 10 4 12 2 4 32 40 544
10 8 6 1 3 1 19 39 331
11 5 6 6 17 48 241
ZON E 1 AVERAGE D ENSITY 411
2 6 4 14 9 2 1 30 50 408
7 7 3 14 2 26 62 285
12 5 8 10 2 1 26 48 368
ZON E 2 AVERAGE D ENSITY 354
3 1 10 3 12 10 1 36 53 462
2 19 2 3 24 51 320
3 10 8 9 9 2 38 56 461
ZON E 3 AVERAGE D ENSITY 414
TOTAL AVERAGE DENSITY 397
14
3.4 Conclusions
Of the forty-eight acres on this site, approximately twenty-five acres involved tree
planting. There were twelve monitoring plots established throughout the planting areas.
The 2003 vegetation monitoring of the planted areas revealed an average density of
397 trees per acre, which is above the minimum requirement of 260 trees per acre.
NCDOT proposes to discontinue vegetation monitoring at the Tucker Mitigation Site.
4.0 OVERALL CONCLUSIONS AND RECOMMENDATIONS
The results of the fifth year of monitoring indicate that the Tucker Tract Mitigation Site is
successful and has met hydrologic and vegetation criteria for the fifth consecutive year.
All of the groundwater monitoring gauges met the success criteria with saturation in the
upper twelve inches for at least 12.5% of the growing season. Also, the data from the
groundwater gauges exhibit similar saturation periods as the reference gauges.
Vegetation monitoring also met the success criteria in the fifth year. The average
density for the twelve monitoring plots (397 trees/acre) was above the required 260
stems/acre.
Based on the hydrologic and vegetation monitoring, the Tucker Tract Mitigation Site met
the success criteria for the site during the 2003-growing season. The site has
demonstrated both hydrologic and vegetation success for five consecutive years.
NCDOT proposes to discontinue hydrologic and vegetation monitoring on the Tucker
Tract Mitigation Site.
15
APPENDIX A
GAUGE DATA GRAPHS
APPENDIX B
SITE PHOTOS
PHOTO AND PLOT LOCATIONS
Tucker Tract
Photo 1 Photo 2
Photo 3 Photo 4
Photo 5 Photo 6
2003

ANNUAL REPORT FOR 2003
Tucker Mitigation Site
Currituck County
Project No. 6.049009T
TIP No. R-2228WM
Prepared By:
Office of Natural Environment & Roadside Environmental Unit
North Carolina Department of Transportation
December 2003
TABLE OF CONTENTS
SUMMARY............................................................................................................1
1.0 Introduction.................................................................................................2
1.1 Project Description...........................................................................2
1.2 Purpose ...........................................................................................2
1.3 Project History .................................................................................4
1.4 Debit Ledger ....................................................................................4
2.0 Hydrology ...................................................................................................5
2.1 Success Criteria...............................................................................5
2.2 Hydrologic Description ....................................................................5
2.3 Results of Hydrologic Monitoring .....................................................7
2.3.1 Site Data ...............................................................................7
2.3.2 Climatic Data.........................................................................8
2.4 Conclusions ...................................................................................11
3.0 Vegetation ................................................................................................11
3.1 Success Criteria.............................................................................11
3.2 Description of Species ...................................................................11
3.3 Results of Vegetation Monitoring ...................................................13
3.4 Conclusions ...................................................................................14
4.0 Overall Conclusions and Recommendations............................................14
TABLES
Table 1 – Tucker Tract Debit Ledger.....................................................................4
Table 2 – 2003 Hydrologic Monitoring Results......................................................7
Table 3 – Hydrologic Monitoring Results (1999-2002) ..........................................8
Table 4 – Vegetation Monitoring Results.............................................................13
FIGURES
Figure 1 – Site Location Map ................................................................................3
Figure 2 – Monitoring Gauge Location Map ..........................................................6
Figure 3 – 2003 Hydrologic Monitoring Results.....................................................9
Figure 4 – 30 – 70 Percentile Graph ...................................................................10
APPENDICES
Appendix A – Gauge Data Graphs
Appendix B – Site Photos/Photo and Plot Locations
1
SUMMARY
The following report summarizes the monitoring activities that have occurred in the past
year at the Tucker Tract Mitigation Site. This is the fifth year that the site has been
monitored for hydrologic and vegetation success. The site must demonstrate both
hydrologic and vegetation success for a minimum of five years to demonstrate
successful mitigation.
The Tucker Tract contains eleven groundwater-monitoring gauges. An Infinity tipping
bucket rain gauge was installed in August 2000. The daily rainfall data depicted on the
monitoring gauge graphs is recorded from this onsite rain gauge. An offsite rain gauge
recorded at Elizabeth City and maintained by the NC State Climate Office, contributed
to the daily rainfall data and historical rainfall data used for the 30-70 percentile. Twelve
vegetation-monitoring plots are used to monitor the twenty-five acres planted in trees on
the site.
The 2003-year represents the fifth growing season that hydrologic data has been
analyzed. All of the groundwater monitoring gauges met the success criteria with
saturation in the upper twelve inches for at least 12.5% of the growing season. Also, the
data from the groundwater gauges exhibit similar saturation periods as the reference
gauges.
At the request of the resource agencies, NCDOT performed supplemental planting of
baldcypress trees in and around plots 8, 9, 10, and 11 (Zone 1) in March 2003. The fifth
year vegetation monitoring of the planted areas revealed an average density of 397
trees per acre, which is above the minimum requirement of 260 trees per acre.
Based on the hydrologic and vegetation monitoring, the Tucker Tract Mitigation Site met
the success criteria for the site during the 2003-growing season. The site has
demonstrated both hydrologic and vegetation success for five consecutive years.
NCDOT proposes to discontinue hydrologic and vegetation monitoring on the Tucker
Tract Mitigation Site.
2
1.0 INTRODUCTION
1.1 Project Description
The Tucker Tract Mitigation Site is located in Currituck County (Figure 1). This site is
part of a large property consisting of 68.3 acres. Approximately 48.1 acres have been
set aside for mitigation. Approximately 28.2 acres of the 48.1 acres were developed
and constructed as the Tucker Tract Mitigation Site. The remaining 20.2 acres will be
reserved for possible future mitigation projects. The site was built to mitigate for the
widening of NC 168 (TIP Project R-2228). The project includes the restoration of 25.1
acres of PC agricultural fields to forested wetlands and the preservation of 2.8 acres of
forested wetlands and 8.7 acres of timbered wetlands.
The Final Mitigation Plan for this site was issued on April 1, 1996. Initial construction
was completed in late 1997. At that time, it was determined that the site had been
graded to an unacceptable level. A second contract was issued and the site was re-graded
in 1998 with completion in September 1998. The site was planted in early 1999.
In March 1999, NCDOT installed hydrologic monitoring gauges. In 2000, two additional
gauges were installed as a result of the field review by the resource agencies. The two
additional gauges were placed to track groundwater in the vicinity of Gauge TT-6.
Gauge TT-6 is located at an elevation that ranges from 0.7 to 1.0 foot higher than the
adjacent topography. This elevated area was delineated with GPS equipment and found
to be 0.09 acres in area. Based on the comments at an agency field review in May
2002, Gauge TT-6 was removed from the site. Twelve plots were established to
monitor vegetation on the Tucker Tract.
1.2 Purpose
In order to demonstrate successful mitigation, hydrologic and vegetative monitoring
must be conducted for a minimum of five consecutive years or until the site is deemed
successful. Success criteria are based on federal guidelines for wetland mitigation.
These guidelines stipulate criteria for both hydrologic conditions and vegetation survival.
The following report details the results of hydrologic and vegetative monitoring during
the 2003-year at the Tucker Tract Mitigation Site, as well as local climate conditions
throughout the growing season.
3
4
1.3 Project History
December 1997 Site Construction Completed (Contract 1)
September 1998 Site Construction Completed (Contract 2)
March 1999 Site Planted, Monitoring Gauges Installed
October 1999 Vegetation Monitoring (1 yr.)
March – November 1999 Hydrologic Monitoring (1 yr.)
August 2000 Vegetation Monitoring (2 yr.)
March – November 2000 Hydrologic Monitoring (2 yr.)
July 2001 Vegetation Monitoring (3 yr.)
March – November 2001 Hydrologic Monitoring (3 yr.)
July 2002 Vegetation Monitoring (4 yr.)
March – November 2002 Hydrologic Monitoring (4 yr.)
October 2003 Vegetation Monitoring (5 yr.)
March – November 2003 Hydrologic Monitoring (5 yr.)
1.4 Debit Ledger
Table 1: Tucker Tract Debit Ledger
Tucker Farm Mit. Plan Ratios TIP DEBIT
Habitat Acres
At Start:
Acres
Remaining
%
Remaining R-2228A, BA
SPH Restoration 25.1 0 0.0 25.1
SPH Preservation 2.8 0 0.0 2.8
Upland Mgmt. 8.7 0 0.0 8.7
TOTAL 36.6 0 0.0 36.6
5
2.0 HYDROLOGY
2.1 Success Criteria
In accordance with Corps guidelines for wetland mitigation, the success criteria for
hydrology state that the area must be inundated or saturated (within 12” of the surface)
by surface or groundwater for at least a consecutive 12.5% of the growing season.
Areas inundated for less than 5% of the growing season are always classified as non-wetlands.
Areas inundated between 5% - 12.5% of the growing season can be
classified as wetlands depending upon factors such as the presence of wetland
vegetation and hydric soils.
The growing season in Currituck County begins March 20th and ends November 13th.
These dates correspond to a 50% probability that temperatures will drop to 28°F or
lower after March 20 and before November 13.1 The growing season is 239 days;
therefore, optimum hydrology requires inundation or saturation for 12.5% of this season,
or at least 30 consecutive days. Local climate must also represent average conditions
for the area.
Based on the mitigation plan, hydrologic success is based on soil saturation that is
similar to the reference ecosystem and in accordance to Corps guidelines. The
reference ecosystem is located onsite in an undisturbed wetland located at a slightly
lower elevation in the southern portion of the site; gauges TT-8 and TT-9 monitor the
reference area.
2.2 Hydrologic Description
There are eleven monitoring gauges and one rain gauge installed onsite (Figure 2).
The automatic monitoring gauges record daily readings of groundwater depth. This is
the fifth year of hydrologic monitoring on the site.
The principal hydrologic source for this site is precipitation with some input from
Buckskin Creek. The Tucker Tract Site involved the grading of the field crowns and
placing the excess into several drainage ditches to prohibit water from leaving the site.
An additional seven to nine inches of fill was brought in to bring the site elevation to its
final grade. Several earthen berms were constructed adjacent to the lower areas of the
site and adjacent to the residential area. This design will restore wetland hydrology,
restrict infiltration losses and surface runoff, and avoid flooding the adjacent residential
area. The hydrologic monitoring should show the reaction of the groundwater level to
specific rainfall events.
1 Natural Resources Conservation Service, Soil Survey of Currituck County, North Carolina, p.71.
6
7
2.3 Results of Hydrologic Monitoring
2.3.1 Site Data
The maximum number of consecutive days that the groundwater was within twelve
inches of the surface was determined for each gauge. This number was converted into
a percentage of the 239-day growing season. The results are presented in Table 2.
Appendix A contains a plot of the groundwater depth for each monitoring gauge and the
surface water depth recorded by the surface gauge. The maximum number of
consecutive days is noted on each graph. The individual precipitation events, shown on
the monitoring gauge graphs as bars, represent data collected from the onsite rain
gauge.
Table 2. 2003 Hydrologic Monitoring Results – Groundwater Gauges
Monitoring
Gauge <5% 5-8% 8-12.5% >12.5% Actual % Dates of Success
TT-1+ r 61.1 March 20-August 12
TT-2 r 46.0 March 20-July 7
TT-3+ r 100 March 20-Nov 13
TT-4+ r 100 March 20-Nov 13
TT-5 r 45.6 March 20-July 6
TT-7+ r 100 March 20-Nov 13
TT-8 (REF)+ r 69.5 March 20-Sept 1
TT-9 (REF)+ r 100 March 20-Nov 13
TT-10 r 23.0 March 20-May 13
TT-11 r 43.5 March 20-July 1
TT-12+ r 100 March 20-Nov 13
+ Gauge met the success criterion during an average rainfall month (July, August, and
October).
*The two reference gauges are shaded.
8
Table 3. Hydrologic Monitoring Results (1999-2002)
Monitoring
Gauge
1999 %
Results
2000 %
Results
2001 %
Results
2002 %
Results
TT-1 16.3 No Data 23.4 26.8
TT-2 17.2 38 10 29.3
TT-3 9.2 25 73.5 53.1
TT-4 21.8 100 61.7 32.2
TT-5 8.8 33 39.1 32.2
TT-6 3 8 4.6 Pulled
TT-7 36.8 100 71.9 35.6
TT-8 (REF) 36 94 61 31.4
TT-9 (REF) 28.9 100 74.4 13.8
TT-10 18.4 33 26.7 26
TT-11 35 28
TT-12 43.8 33
Climate
Conditions
Average
Rainfall
Average
Rainfall
Below
Average
Rainfall
Average to
Below
Average
Rainfall
*The two reference gauges are shaded.
Table 3 is a summary of the hydrologic gauge data representing previous years (1999-
2002).
Figure 3 provides a graphical representation of the hydrologic results. Gauges
highlighted in blue indicate wetland hydrology for more than 12.5% of the growing
season. Gauges highlighted in red show hydrology between 8% and 12.5% of the
growing season, while those in green indicate hydrology between 5% and 8%. Gauges
highlighted in gray indicate no wetland hydrology (less than 5% of the growing season).
2.3.2 Climatic Data
Figure 4 is a comparison of monthly rainfall for the period of November 2002 through
November 2003 to historical precipitation (collected between 1972 and 2003) for
Elizabeth City, North Carolina. This comparison gives an indication of how 2003 relates
to historical data in terms of climate conditions. The NC State Climate Office provided
all local rainfall information.
For the 2003-year, January (02’) and November experienced below average rainfall.
The months of December (02’), July, August, and October recorded average rainfall for
the site. November 02, February, March, April, May, June, and September experienced
above average rainfall. Overall, 2003 experienced an average to above average rainfall
year.
9
Figure 3. 2003 Hydrologic Monitoring Results
10
FIGURE 4. 30-70 Percentile Graph
Tucker 30-70 Percentile Graph
Elizabeth City, NC
0
1
2
3
4
5
6
7
8
9
10
Nov 02' Dec 02' Jan 03' Feb 03' Mar 03' Apr 03' May 03' Jun 03' Jul 03' Aug 03' Sep 03' Oct 03' Nov 03' Dec 03'
Month
Precipitation (in.)
2002 Rainfall 2003 Rainfall 30th Percentile 70th Percentile
30th Percentile
70th Percentile
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2.4 Conclusions
The 2003-year represents the fifth growing season that hydrologic data has been
analyzed. All of the groundwater monitoring gauges met the success criteria with
saturation in the upper twelve inches for at least 12.5% of the growing season. Also, the
data from the groundwater gauges exhibit similar saturation periods as the reference
gauges.
This is the fifth consecutive year that the site hydrology has met the success criteria;
therefore, NCDOT proposes to discontinue hydrologic monitoring.
3.0 VEGETATION: TUCKER TRACT MITIGATION SITE
(YEAR 5 MONITORING)
3.1 Success Criteria
NCDOT will monitor the site for five years or until success criteria are met. A 320 stems
per acre survival criterion for planted seedlings will be used to determine success for
the first three years. The required survival criterion will decrease by 10% per year after
the third year of vegetation monitoring (i.e., for an expected 290 stems per acre for year
4, and 260 stems per acre for year 5). The number of plants of one species will not
exceed 20% of the total number of plants of all species planted.
3.2 Description of Species
The following tree species were planted in the Wetland Restoration Area:
Zone 1: Wetland Reforestation (14.05 Acres)
Fraxinus pennsylvanica, Green Ash
Quercus falcata var. pagodaefolia, Cherrybark Oak
Quercus michauxii, Swamp Chestnut Oak
Quercus phellos, Willow Oak
Quercus nigra, Water Oak
Quercus lyrata, Overcup Oak
Nyssa aquatica, Water Tupelo
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Zone 2: Wetland Reforestation (9.04 Acres)
Taxodium distichum, Baldcypress
Fraxinus pennsylvanica, Green Ash
Quercus falcata var. pagodaefolia, Cherrybark Oak
Quercus michauxii, Swamp Chestnut Oak
Quercus phellos, Willow Oak
Quercus lyrata, Overcup Oak
Zone 3: Wetland Reforestation (1.89 Acres)
Quercus phellos, Willow Oak
Quercus nigra, Water Oak
Fraxinus pennsylvanica, Green Ash
Taxodium distichum, Baldcypress
Quercus lyrata, Overcup Oak
Nyssa aquatica, Water Tupelo
Quercus michauxii, Swamp Chestnut Oak
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3.3 Results of Vegetation Monitoring
Table 4. Vegetation Monitoring Results
Site Notes: Site is well vegetated with various grasses, a variety of Juncus sp., and
sedges. 6 to 8 inches of standing water noted in a small area of plot 7. Other species
noted: volunteer pines, Scirpus sp., Aster sp., cattails, Baccharis halimifolia, foxtail,
woolgrass, fennel, pickerel-weed, Cyperus sp., pennywort, Panicum sp., Lespedeza sp.,
red maple, sawgrass, and Sesbania sp.
At the request of the resource agencies, NCDOT performed supplemental planting of
baldcypress trees in and around plots 8, 9, 10, and 11 (Zone 1) in March 2003.
1 4 12 2 8 5 5 32 55 396
5 1 10 10 10 2 33 48 468
8 16 10 1 5 5 37 52 484
9 10 4 12 2 4 32 40 544
10 8 6 1 3 1 19 39 331
11 5 6 6 17 48 241
ZON E 1 AVERAGE D ENSITY 411
2 6 4 14 9 2 1 30 50 408
7 7 3 14 2 26 62 285
12 5 8 10 2 1 26 48 368
ZON E 2 AVERAGE D ENSITY 354
3 1 10 3 12 10 1 36 53 462
2 19 2 3 24 51 320
3 10 8 9 9 2 38 56 461
ZON E 3 AVERAGE D ENSITY 414
TOTAL AVERAGE DENSITY 397
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3.4 Conclusions
Of the forty-eight acres on this site, approximately twenty-five acres involved tree
planting. There were twelve monitoring plots established throughout the planting areas.
The 2003 vegetation monitoring of the planted areas revealed an average density of
397 trees per acre, which is above the minimum requirement of 260 trees per acre.
NCDOT proposes to discontinue vegetation monitoring at the Tucker Mitigation Site.
4.0 OVERALL CONCLUSIONS AND RECOMMENDATIONS
The results of the fifth year of monitoring indicate that the Tucker Tract Mitigation Site is
successful and has met hydrologic and vegetation criteria for the fifth consecutive year.
All of the groundwater monitoring gauges met the success criteria with saturation in the
upper twelve inches for at least 12.5% of the growing season. Also, the data from the
groundwater gauges exhibit similar saturation periods as the reference gauges.
Vegetation monitoring also met the success criteria in the fifth year. The average
density for the twelve monitoring plots (397 trees/acre) was above the required 260
stems/acre.
Based on the hydrologic and vegetation monitoring, the Tucker Tract Mitigation Site met
the success criteria for the site during the 2003-growing season. The site has
demonstrated both hydrologic and vegetation success for five consecutive years.
NCDOT proposes to discontinue hydrologic and vegetation monitoring on the Tucker
Tract Mitigation Site.
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APPENDIX A
GAUGE DATA GRAPHS
APPENDIX B
SITE PHOTOS
PHOTO AND PLOT LOCATIONS
Tucker Tract
Photo 1 Photo 2
Photo 3 Photo 4
Photo 5 Photo 6
2003